1. Preheat the oven to 180C (fan) 200C, Gas mark 6. Line the loaf tin with baking parchment.2. Break up the walnuts a little and mix then with all the cake ingredients together in a large bowl with a spoon.3. Pour into the tin and bake for 50 -60 minutes till golden.4. Leave to cool in the tin while you mix the cream cheese, icing sugar and lemon zest together for the topping.5. When the cake is completely cold top it with the creamy icing.